Machine tool



July 31, 195] E. J. BUSEMEYER 2,562,170

MACHINE TOOL Filed Sept. 30, 1946 Sheets-Sheet 2 INVENTOR. EDWARD J.' BusE ME YER lllll w J. BUSEMEYER July 31, 1951 MACHINE TOOL 7 Sheets-Sheet 5 Filed Sept. 30, 1946 INVENTOR. EDWARD J. busamavan Attorney.

J y 1951 E. J. BUSEMEYER 2,562,170

MACHINE TOOL Filed Sept. 50; 1946 7 Sheets-Sheet 4 INVENTOR. EDwA'tzD J. buszmzvzn Attorney.

July 31, 195] E. J. BUSEMEYER 2,562,170

MACHINE TOOL Filed Sept. 30, 1946 v 7 Sheets-Sheet 7 IN VEN TOR.

EDWARD J. buaanzvzn %&/2w, Attorney.

Patented July 31, 1951 MACHINE TOOL Edward J Busemeyer, Cincinnati, Ohio, assignor to The Aver D illin Machine C mpan oving on, Ky" a corpora i n of hio Application September 30, 1246, Serial No. 700,223

11 Claims.

This invention relates to improvements in ma.- ohine tools and particularly to improvements in hi h spe d r sensitive drilling machines.

n the pas there have be nprovided high sp drill g machines for performin deep ho or p rillin perations. As is w ll known st p drilling contemplates a drilling machine wh the drill or tool is actuated through. shor drilling steps without causing the drill or tool to completely penetrate the work. It has been found that t set up definite interva s of s p rill n consumed more time than was desirable since to be safe the actual drilling time was reduced to a. minimum while in the majority of cases this drilling step could have continued for a considerably longer time without endangering the drill, tool or work.

It has further been proposed to augment the control of the tool feed by utilizing the torque on the drill as a means for effecting the withdrawal of the drill from the work. Such a mechanism is disclosed in United States Patent 2360 32? which issued on- October 28, 1941, to George K. McKee. While the mechanism as disclosed in the above mentioned patent a considerabl improvement over the prior known structures the torque sensitivity was not up to that desired and the present invention, is an improvement on the disclosure therein and in which the sensitivity more nearly approaches the desired torque control. By the present invention all of the ad vantages of the heretofore known step drilling machines are retained plus the extr me s nsitivity to torque on the drill during the actual drilling or tooling operation.

It is, therefore,- the principal object of the present nvention to provide a step drilling machine in which the resistance on the .drill to drill rotation efiects the withdrawal of the drill from the work.

Another object of this invention is to provide a high speed or sensitive drill for deep hole or step drilling operations in which the drill is withdrawn at regular intervals for chip clearance and drill cooling in addition to the withdrawal of said tool or drill when-the torque thereon approaches the breaking point of the drill.

It is also anobject of this invention to provide a machine for accomplishing the foregoing objects which is economical to manufacture and comparatively simple in .its operation.

A still further object of the present invention is the provision of a device for accomplishing the foregoing objects which can be adjusted whereby the sensitivity thereof maybe varied depending upon the size of the drill, material of 2 which the drill is made and the material being operated upon.

Other objects and advantages of the present in vention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings forming a part thereof and it is to be understood that any modifications maybe made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

In the drawings:

Fig. 1 is a front elevation of a high speed or sensitive drilling machine embodying the improvements of this invention.

Fig. 2 is a side elevation of the machine of Fig. 1 as seen from the right hand side of said Fig. 1.

Fig. 3 is a plan view of the spindle rotating and driving mechanism as seen from line 31-3 on Fig.2.

Fig. 4 is a view partly in section and partly in elevation through the spindle drive as seen from line led on Fig. 3.

Fig. 5 is an enlarged sectional view of a portion of Fig. 4 and particularly illustrating the spindle driving mechanism as supported thereby.

Fig. 6 is a view partly in section and partly in elevation of the right hand side of Fig. 5 as seen from line 6-45 on said Fig. 5.

Fig. 7 is a View similar to Fig. 6 showing the parts in a second position from that of Fig. 6.

Fig. 8 is a transverse sectional view through he pindle driving mechani m as. seen from line 8-4! on Fi 5,. I

Fi 9 is a top plan view of he spindle drive mechanism; wi h t e p r in he pos n illustrated in Figs 5, 6 and 7.

Fig. 10 is a side elevational view of an enlarged cale of the spindle carryin he d.

Fig. 11 is a op plan view f the tool head 0 Fig. 10.

Fig. 12 is an enlarged vertical sectional View through the spindle carrier as seen from line |2-I2 on Fig.1.

Fig. 13 is a transverse sectional view through the tool head taken on line l3--I3 on Fig. 10.

Fig. 14 is a vertical sectional view through the tool head taken on line I4M on Fig. 11 and illustrating the main control valve.

Fig. 15 is a transverse sectional view through the 'tool head taken on a plane ahead of that of 3 the tool head taken on a plane behind that of Fig. 14 on line Iii-46 on Fig. 11.

Fig. 17 is a fragmentary vertical sectional view through a part of the control mechanism taken on line i'i--ll on Fig. 15.

Fig. 18 is a fragmentary transverse sectional view through the tool head taken on line lit-43 on Fig. 15.

Fig. 19 is a fragmentary transverse sectional view through the tool head taken on line i3-l3 on Fig. 10.

Fig. 20 is a fragmentary vertical sectional view taken on line 2ll20 on Fig. 10.

Fig. 21 is an enlarged fragmentary transverse sectional view illustrating the relative positions of the control torques as seen from line 2I-2l on Fig. 10.

Fig. 22 is a vertical fragmentary view partly in section and partly in elevation through the control torques as seen from line 22-22 on Fig. 10.

Fig. 23 is a fragmentary enlarged transverse sectional View through a part of the torque control mechanism as seen from line 2323 on Fig. 10.

Fig. 24 is an enlarged fragmentary vertical sectional view through the tool head as seen from line 24--24 on Fig. 13.

Fig. 25 is an enlarged sectional view through a part of the torque operating system taken on line 25 25 on Fig. 10.

Fig. 26 is a diagrammatic view depicting the complete hydraulic and electrical circuits utilized in effecting and controlling the movements of the drill or tool carrier.

Throughout the several views of the drawings, similar reference characters are employed to denote the same or similar parts.

As was noted above, this invention pertains primarily to means or mechanisms for controlling the longitudinal or feed movement of a drill for performing step or deep hole drilling operations. In the embodiment of the invention here-- in disclosed there is provided a machine in which the tool or drill is advanced from an initial positon at a rapid rate to the work, fed at a slow rate through a part of the work and then retracted, followed by a rapid advance of the drill or tool to the point where it was previously withdrawn for a second drilling step whereupon reversal again takes place. This cycle of operation is repeated until the work is completely tooled or drilled. As was noted above, the purpose of this type of a control mechanism is to permit the clearing of chips from the holes so that they do not interfere with the rotation or'operation of the drill or interfere or prevent maintaining the drill in a cool condition. In the case of drilling oil holes in crank shafts, this is very important since such drills are of comparatively small diameter and will not stand a great amount of strain. In this instance, the chips may interfere with the rotation of the drill, thereby setting up a torque on the drill in excess to that which it will stand, causing said drills to be twisted and broken.

By the present invention, means are provided whereby this torque is utilized for effecting the withdrawal of the drill from the hole. At the same time, these chips may not increase the torque on the drill but might interfere with the proper feeding of the drill, thereby causing same to become excessively hot, and means are therefore provided supplementary to the torque control means for periodically withdrawing the drill fromthe hole to provide for cooling of the drill.

The machine disclosed in the drawings is a single spindle machine, that is, a machine for drilling one hole at a time. It should be noted, however, that a multiple spindle machine may, and in fact has been, produced in which a plurality of drilling heads were employed, thereby simultaneously drilling a comparatively large number of holes, such as the oil holes for all of the bearings of a crank shaft as used in a multiple cylinder internal combustion engine, and in which each drilling head had incorporated therewith the control means to be presently described.

Specifically, the machine shown in the drawings comprises a base 25, from which rises a standard 26 having formed vertically of its front face a dovetail guide 21 having mounted thereon a Work supporting table 28. Any suitable means (not shown) may be provided for adjusting the work table 28 relative :to the guide 21 and for clamping the table in position. Mounted on the upper end of the standard 26 is a column 29 terminating at its upper end in a housing 30 for the spindle bearings and like mechanism.

The column 23, at its upper rear end, is provided with a pad 3| to which is secured a motor 32. Projecting from the motor 32 is the motor shaft 33 which projects into a hollow cover cap 34 secured to the housing 30. The motor shaft 33 has keyed or otherwise secured to it a pulley 35 for a belt 36. The belt 36 is in turn extended around the spindle pulley 31, freely rotatable on anti-friction bearings 38 which encircle the spindle sleeve 39. The spindle sleeve 39 is journaled in anti-friction bearings 40 and 4| and is provided interiorly thereof with suitable driving keys which enter splines in a spindle 42.

The spindle pulley 31 is substantially cup shaped and encloses the anti-friction bearing 38. The inner race of the bearing 38 is placed under tension by a nut 43 which has its sleeve like portion 44 in contact with said inner race of antifriction bearing 38. The nut 43 is connected with the spindle sleeve 39 through threads 45. The nut 43 includes an enlarged portion 46 which carries the driven means between the pulley 31 and spindle sleeve. As seen most clearly from Fig. 8 the nut portion 46 has projecting, radially, from equally spaced points around its periphery, three being shown, studs 41, 48 and 49 on each of which is mounted a driven cam or dog 53. Each of said cams or dogs 50 is substantially identical which, as seen in Figs. 5, 6 and 7 comprises a cylindrical member or roller 5| having at one point on its periphery a flat 52. Diagonally opposite the flat 52 the cam or dog is provided with a vertical shoulder or face 53 which terminates in an upwardly and outwardly inclining cam face 54. The dog is mounted on its stud 41, 48 or 49 through an anti-friction bearing 55.

Projecting upwardly from the hub 56 of the spindle pulley 31 is an abutment 51 in the nature of a roller secured to the pulley 3! through a threaded stud 58. There are as many abutments 51 as dogs 55. Each abutment 5! is positioned on the pulley 31 to be engaged by the vertical shoulder or face 53 of the cam or dog rollers 5i.

Surrounding the spindle driving sleeve 39 is a plate 59 having its under surface 60 simultaneously resting on the flats 52 of each of the cams or dogs 50. Upstanding from the plate 59 is a short sleeve 6! which acts as a centralizing medium for a coiled spring 62 above the plate 59. The

' other end Of the spring 62 is likewise centralized by a short sleeve 63 projecting downwardly from a nut 64 on the spindle sleeve 39.

The spring tensioning nut 64. is provided with a screw 65 having projecting therefrom a pin like portion 66 that enters the screw thread or spiral path 61 in the upper end of the spindle sleeve 39. The screw thread or spiral path 61 has a large lead whereby the nut may be rapidly advanced longitudinally of the spindle driving sleeve. The nut 64 is adapted to. be actuated to the desired positionand then secured in this position for which purpose it is split as at 68, see Fig. 9,, have ing the split spanned by a Suitable clamping screw 69. Upstanding from the housing 30 is a post 18 having secured. to its. upper end,'as by nuts 'll, an; angle bracket 12. The one leg 13 of the angle bracket 12 has secured -to it. a micro-electric switch ,14 which has pivoted, thereto one end of an arm 15. Projectingfrom the arm 15 is a plunger 16 to actuate the switch contacts within the micro-switch, not shown except diagonally in Fig. 26 where they are indicated by the reference numeral 1?. The other end of the arm 15 is provided with a roller 18 which rides on the upper surface of the plate 59 as clearly illustrated in Figs, 5 and 7.

. The motor 32 rotates in a clockwise direction as indicated by the arrow 80 onv Fig. 3 Which through the belt 38 correspondingly rotates the spindle sleeve pulley 31. The rotation of the spindle sleeve pulley 31 in a clockwise direction is to the left as seen in Figs. 5, 6 and 7 wherefore the abutments 51, from; said pulley 31, will each-engage its driven cam or dog 50 through their shoulders or vertical faces 53 to correspondingly rotate the nut .43 and thereby the spindle sleeve 39. The position of the parts illustrated in Figs. 5 and 6. the normal or idle position and upon initial rotation of the spindle sleeve pulley 31 the cams. or dogs 50 are slightly rotated about their individual studs 41, 48 and 49 to the position shown in solid lines in Fig. "I. In other words the flats 52 of each cam or dog 50 is slightly tilted from the horizontal to a.

downwardly inclined position as seen in Fig. 7 in solid lines which causes a slight compression in the spring, 52. It is in this position of the parts that the spindle is being rotated during a drillin operation. The parts will be held in this position so long as the drill is freely cutting and has no torque or sticking pressure thereon greater than that which can be withstood by the drill.

Should, for somereason, the torque on the drill be increased due to a'gathering of the chips in the, hole being drilled or a swelling of the drill dueto friction heat or for any other reason a resistance beset upto drill rotation, the driving spindle sleeve will tend to slow down in its rotation thereby tending to correspondingly slow down the rotation of the spindle sleeve pulley 31. Since the said spindle sleeve pulley is being constantly driven through the belt 36 the abutments 5'! will, constantly turn and will thereby cause the cams or dogs 5ll to be rotated or oscillated about their studs 41, 48 and .9 from the solid line position of Fig. '7 to the phantom line position 8| thereof and willthereby raise the plate 59 from its solid line position in Fig. 'l to its phantom line position, indicated by the reference numeral 82, and correspondingly elevate the micro-switch arm 19 from its solid line position to its phantom line position 83. This immediately closes the contacts of the microswitch to operate the control mechanism, to be later described, and withdraw the drill from the work.

It has. ben found in actual tests that this control is an extremely accurate and sensitive one. For example use was made of a one-eighth inch drill rotating at 2750 R. P. M. and that in a maximum of ten revolutions of the drillthe withdrawal took place. This withdrawal was efiected in five one-hundredths (.05) of a second, the total. time required to actuate the micro-switch and effect the said drill withdrawal. The break down of this time included twelve thousandths (.012) ofa second for switch operation and twenty-nine thousandths (.029) of a second for solenoid operation, to be later described. g

It is to be understood. of course, that this time may be varied depending upon the size of the drill and the materials being used and which variation is accomplished by adjustingthe nut 64 to increase or decrease the tension in, the spring 62. all as pointed out above.

From the foregoin it will now be appreciated that there has been provided a yieldable drive connection between a source of power and, the spindle and which drive connection yields to eX- cessive pressure on the drill due to an increase in torque thereon. It will further be appreciated that by adjusting the tension or yielding limit in this yieldable drive drill breakage can be so utilized that the drill is withdrawn in ample time to prevent the occurrence of drill breakage. It will further be appreciated that a high speed or sensitive drilling machine equipped with the yieldable drive just described will perform drilling operations of the step drilling type and the actual drilling performed until the point of breakage of the drill is nearly reached instead of withdrawing the drill when no danger exists.

The spindle 42 is mounted for rotation, at its lower end, in a quill 84, disposed for axial adiustment in a bore in a tool carrier 85, see Fig. 12. The upper end of the tool carrier carried an anti-friction bearing BSfor the spindle 42. The lower extremity of the spindle 42 is provided with the usual chuck 81 for the drill or other tool. 7

The spindle 42 is axially adjustable relative to the carrier 85 by means of a rack pinion 88 carried by a shaft 89 rotatably journaled in the carrier 85. The rack pinion 88 meshes with a rack 90 formed integral with or secured to the quill 84 In order to rotate the pinion '88, its shaft 89 projects beyond the forward side of the carrier 85 and has secured thereto a knob or the like 9|. The lower end of the carrier is split, and on each side thereof are lugs or ears 92 and 93, see Fig. 13, respectively provided with a tapped and a plane perforation receiving a clamping stud 94. This clamping stud draws the portions of the carrier on each side of the split 95 towards one another and thereby clamps the quill in adjusted positions.

The spindle carrier, and therefore the parts carried thereby, are actuated by hydraulic means toward and from the work, which means, as shown in Fig. 12', comprises a rearwardly projecting lug 96 on the carrier 85 which has a perforation therein receiving the lower, reduced end 91 of a piston rod 98. The piston rod 98 has secured to its upper end a piston 99 which is movable through a cylinder l 00 secured in a bore in the tool head llll.

In order to prevent loss of fluid and pressure around the piston red at its lower end, usefis made of a suitably packed joint l0; carried by the lower cylinder head I03. The upper'end'of the cylinder I is likewise suitably closed by a head I04.

The spindle carrier 85 is guided in its movement relative to the tool head IilI, see Fig. 11, by means of a dove-tailed guide I received in a correspondingly shaped guide-Way I06 with a gib I0! between one side of the guide and the adjacent side of the guide-way. The tool head I 0| is provided in its rear side with a dove-tailed guide-way I08 receiving a correspondingly shaped guide I09 formed on the forward face of the column 29. A gib H0 is disposed in the guide-way I08 between one side of the guide tongue I09 and the opposed side of said guide-way I08 for clainping the head in position on the said column 29.

As was noted above, hydraulic or fluid means is preferably employed for actuating the piston 56, and therefore the spindle carrier, toward and from the work. This hydraulic mechanism is shown diagrammatically in Fig. 26 to which reference is now to be had, and the various valves and control means will be described in detail with reference to their structural illustrations in the other figures of the drawings as they are encountered in a complete cycle of operation of the machine. As shown in Fig. 26, use is made of a tank or sump III, which may be independent of the machine though preferably is formed in some part of the bed, such as in the base 25 and lower portion of the standard 20. Mounted above the tank or sump I I I is a constantly rotating pressure circulating pump H2 having its intake or suction side connected by a pipe I i3 with the sump or tank. The discharge side of the pump has extending therefrom the pressure pipe or conduit H4, terminating in the main control mechanism indicated in general in Fig. 26 by the reference numeral H5. The pressure pipe or conduit II4 has connected therewith a branch pipe or conduit I I6 which terminates in the sump or tank I I I, and has intermediate its ends an adjustable relief valve H1. The relief valve II'I .determines the actuating pressure in the system.

The main control valve I I5 is structurally illustrated in Fig. 14 and comprises a valve block I I3 secured to the inner face of a plate H9 which closes the open right hand end of the tool head IOI, as seen in Figs. 1 and 14. Pressed into a suitable bore in the valve block H8 is a valve sleeve I20 having formed therethrough and radially thereof a plurality of sets of radial ports I2I, I22, I23, I24, I25 and I26, each set of ports being encircled by a similar groove I27 formed circumferentially in the exterior of the sleeve I20. Disposed in the bore of the valve sleeve I20 is a spool type valve member I 20 provided with reduced portions or cannelures I29, I30 and I3I adapted in different positions of adjustment to variously connect the several sets of ports in the valve sleeve I20.

The valve I28 has four operative positions, and in order to determine these positions, it has projecting therefrom a stem I32 provided with V- shaped notches I33 co-operating with a spring pressed detent I34 carried by a valve block I35. The valve block I35, similar to the valve block H8, is secured to the inner face of the plate H9, and therefore projects into the interior of the tool head IN. The position of the valve illustrated in the drawings is the neutral or stop position, and the valve has a position to the right of that shown in Fig. 26, or below that shown in Fig. 14, which is the retracting position. In order to limit the movement of the valve to the right in Fig. 26, and downwardly in Fig.14, use

is made of a stop screw I36 carried by the valve block I35 in alignment with the valve stem I32. A third position of the valve I28 is to the left of that shown in Fig. 26 and upwardly of that shown in Fig. 14, which is the slow feed position to cause the tool to feed slowly through the work While a cut is being effected. The fourth position of the valve is to the extreme left in Fig. 26, and extreme upper position in Fig. 14, which is the rapid downward position to cause a rapid approach of the tool to the work. This fourth position is finally determined by a stop screw I31 threaded into the upper wall of the tool head IOI.

As seen in Fig. 26, the radial ports I22 and I24 have respectively connected with them one end of pipes or conduits I38 and I39 which respectively terminate at ports located at upper and lower ends of the piston cylinder I00. The ports I23 have connected therewith the upper end of the main pressure pipe or conduit H4, while the ports I2I and I 26 have connected therewith pipes or conduits I40 and MI which terminate in the sump or tank III, and are, therefore, the return lines for the system from the main control valve mechanism. The remaining set of ports I25 of the piston valve sleeve I20 have connected therewith one end of a pipe or conduit I42 which terminates in a balance valve mechanism, indicated in general in Fig. 26 by the reference numeral I43, and which will be described in detail later.

At the commencement of a tooling cycle, the valve I28 is manually shifted by means of a lever I44, see Fig. 13, which is keyed or otherwise secured to the outer projecting end of a shaft I45 oscillatably journaled in a bushing I46 carried by the tool head cover plate I I 9. The inner, projecting, end of the shaft I45 has keyed or otherwise secured to it a lever I41 having at its free end a valve shifting pin I48 received in a slot I49 formed in the valve stem I32. This initial shifting of the valve member I28 is to the extreme left in Fig. 26 and extreme upper position in Fig. 14 for thereby connecting the pressure ports I23 with the ports I22 and causing a flow of fluid from the conduit I I4 to the conduit I33, and therefore the upper end of the cylinde I00 for actuating the piston 99 downwardly together with the parts connected therewith. The fluid beneath the piston 09 is at this time being exhausted by way of pipe or conduit I33 to the ports I24 and I26 and to the pipes or conduits MI and I40 to the sump or tank III. As was noted above, this movement of the piston and parts connected therewith is at a rapid rate in a downward direction or toward the work.

The rapid downward or advance movement of the carrier continues until the drill or tool is about to strike the work, whereupon this movement is changed to a relatively slow feed rate of movement. In order to accomplish this, the tool carrier is provided therein with a T-shaped slot I50, see Fig. 11, which extends the length of the carrier and has secured therein at its upper end a bracket or arm I5I, and at its lower end a bracket or arm I52, see Fig. 19. Carried by the brackets or arms I5I and I512 is a rod or bar I53, shown in the drawings as of angular cross section. Mounted on this rod is the cumulative rapid traverse stop dog I54 which, as seen in Fig. 10, is provided with a cam shaped nose I55 on one side of the rod I53, and as seen in Fig. 24 with a cylindrical boss I56 on the other side of said rod I53. The boss I56 is hollow to accommodate a friction shoe I5'I backed up by a spring I58 Whose tension may be adjusted by screw I59. The cam nose I55 provides an inclined cam face I60 for engagement with a flipper dog I6I. The flipper dog I6I, as seen in Figs. 10 and 20, is secured to the outer end of a stud I62 oscillatably iournaled in the tool head plate II 9. The flipper dog I6I is provided with a notch I63 receiving the ball end of a projection I64 extendingfrom the lever I44.

From this, it will be seen that the cumulative rapid traverse stop dog I54 -is adjustably positioned on the rod I53 to engage the flipper dog 'I6I at the point where the drill or tool is about to engage the work. The oscillation of the Hipper dog I6I in a counterclockwise direction, as seen in Fig. '10, actuates-the lever in a clockwise direction, which through the shaft or stud I45 and arm I41,'shifts the valve member I28 to a position for cutting oil the flow of the exhaust fluid through the pipe or conduit I39 and therefore the unrestricted port I24. This flow is directed, instead, from the pipe or conduit I39 :tothe feed rate determining valve, indicated in general in Fig. 26 by the reference numeral I65.

This feed determining valve I65 is shown structurally in Fig. 16, and comprises avalve block I66 secured to the rear side or end of valve block I28, as shown in dotted lines in Fig. 11 The valve block I66 is provided therethrough with a pair of boresI61 and I68, one end of each of which is closed by a plate I69, while the other ends are in-communication with a chamber I10. This chamber I10 is in turn closed by a plate .I1I secured to the block I66. Disposed in the valve block bore I61 is a valve member I12 having an inclined groove I13 formed longitudinally in one side thereof. The valve member I12 .is provided adjacent one end of its groove with an enlarged threaded-portion I14 threaded .into an aperture I15 formed through the closure plate =.I;1I. Projecting from the threaded portion I14 is the valve stem I16, having its end provided with a portion to receive a suitable wrench, key or the like whereby the Valve may be turned to effect its adjustment through its enlarged threaded portion I14.

The most shallow portion of the groove I13 is adjacent to the chamber I19 and establishes the minimum rate of flow from this chamber. From this, it will be seen, that the greater the depth of the groove I13 that is in communication with the chamber I10, the faster the flow from this chamber, and that the position of this groove with respect to the chamber I10 is determined by the adjustment of the threaded portion I14 on the valve stem I12 and therefore the rate of flow of the fluid and the rate of feed of the'drill or tool. This chamber I10 is shown diagrammatically in Fig. 26 as a port I10 to which is connected one end of a pipe or conduit I11'which has its other end connected with the pipe or cgnduit I39 from the lower end of the cylinder I 0.

The valve block I66 is shown as provided with a port I18 between the valve block bores I61 and I68. This port I18 is diagrammatically illustrated in Fig. 26 as a pipe or conduit I19 connecting the valve bore I61 ahead of the valve member I13 with the bore I68 which contains the balance valve mechanism, indicated in general in Fig. 26 by the reference numeral I43.

. The balance valve mechanism I43 is illustrated structurally in Fig. 16, and comprises a valve member I80 disposed in the valve bore I68 of valve block I66 andwhich valve member has reduced stem portions I8I-and I82 at opposite ends thereof, together with a reduced central portion or cannelure I83..- This reduced portion or cannelure controls the flow through a port, shown most clearly in Fig. 26 by the reference character I84, with which is connectedthe pipe or conduit I42. Thevalve block I46 is shown in-Fig. 16 as having a second port I95 connecting the valve bores I61 and I68, this port being diagrammatically shown as a conduit I86 in Fig. 26, and connects the space ahead of the valve member I12 with the space ahead of the valve member I80. The'space ahead of the valve member I80, and including the-reduced portion I82, includes a spring I81 which surrounds the said reduced valve portion I82 and abuts against the closure plate I69 for urging thevalvemember I86 tothe right, as seen in Fig..16, or downwardly as seen in Fig. 26, maintaining the port I84 normally open. As will be seen in Fig. '16,.the fluid chamber I10 is at all times in communication with the end of the valve member I80, and this chamber is illustrated in Fig. 26 by means of a port I10" with which is connected one end of a pipe or conduit I88 which has its other end connected with the pipe or conduit 139 The operation of the balance valve mechanism is well understood-its purpose being to maintain a constantflow 0f fluid'through the system when the tool is being actuated through a slow or feeding cycle. This flow from the exhaustpipe or conduit I39 from thecy-linder .I 06 is by way ofthe pipes or conduits I11 and. I88 to the chamber I 1.0 where it 'actson thebalance valve I 80, for actuating it against the resistance of spring I81, and flows through the grow/e113. The flow through thegroove I13 is :through the ports I18 and I85 respectively and pipes criconduits I19 and 1-86. The flow through the port. I85 orpipeor conduit I86 combines withtheyieldable urgeof the spring IB'I-forrshifting the valve-against the pressure in chamber I18 and therefore opening the'port 1.84 an :amount equal .torthe balance in pressure -at the. two endseof thevalve'as determined by the adjustment of'the valve'member. I12. This flow throughtheport I84 is .into the pipe or conduit I42 to the main control valve *mechanism II5 where it is connectedwiththe pipes or conduits MI and I40 and thesumportank III...

. The slow! feeding movement of the toolcontinues until the tool carrieris reversed for withdrawing the; tool from the work. The reversal of the tool carrier may be accomplished through either of two instrumentalities, either after a definite amount of slow feed has taken place, or When-the torque on the drillreaches a point nea the safe .torque loadon thedrill. Since the torque drive on the spindle and it control'have been..p reviously' described its connection .with the operating mechanism will first be disclosed.

Within the microswitch housing is a pair of fixed contacts showndiagrammatically in Fig. 26 and indicated by the reference numeral I89. shown in Fig. '26 the movable contacts 11 have respectively connected therewith the power lines 1'96 and I9 For an electrical supply, while the fixed contacts I89 have respectively connected therewith wires I 92 and I 93 respectively connecting the opposite-end of thewinding of the coil of solenoid Ihe solenoid I94, as seen in Fig. 10, issecured to the lower end of "tool-head plate II9-and has the core I95 projecting'therefrom. -The'upper end of-lthe cor'e .I 95 is pivotally connected at -I 96 l l with a link I91. The upper end of the link I91, in turn, i pivotly connected at I98 with an extension I99 of the manually operating lever I44.

It should be noted that the spindle rotating or driving belt 36 is tensioned to the point of continuing drill rotation to at least the point of drill breakage so that any slowing down in spindle rotation is caused by excessive torque on the drill. For this purpose the slack side of the belt has contacting therewith the idler or tensioning pulley or roller 200 rotatably mounted at the free end of an arm 20I oscillatably mounted on a stud 202 carried by and upstanding from the housing 30. Also mounted on the stud 202 and connected with the arm 29I is a segmental gear 293 having its teeth enmeshed with a worm 204 on the inner end of a worm shaft 205. The worm shaft 205 is rotatably journaled in suitable bearings provided by the housing 30 and which shaft 205 has secured to its projecting free end an operating knob 206.

From the foregoing it will now be seen that a slowing down of the spindle 42 due to an increase in torque on the drill or other tool which causes the closing of the microswitch contacts I! and I8I will operate the solenoid I94 and thereby shift the main control valve mechanism I I to the right, as seen in Fig. 26, and effect thereby a rapid retraction of the piston 99 and parts carried thereby. It is believed obvious that the shifting of the main valve mechanism H5 will effect this operation since the pressure in pipe or conduit H4 will be connected with the pipe or conduit I39 and the under side of the piston 99. The exhaust fluid from the other side of the piston 99 flows through pipe or conduit I38 to the pipe or conduit I40 and the sump III.

The rapid retraction of the spindle carrier and parts associated therewith continues until the carrier is reversed to again descend to work drilling position. The means and mechanism disclosed in the drawings for effecting this reversal includes an arm 201, secured to the lower end of the dog rod I53. The arm 20? has upstanding from its free end an abutment pin 208 adapted to engage the lower end of a pin 209, illustrated most clearly in Figs. and 25. The pin 209 is mounted in a cylindrical portion or housing 2I0, at the end of an arm 2II pinned or otherwise secured to an oscillatable rod 2I2. The rod 2I2 is journaled for oscillation at its upper end in a bracket 2 I3 carried by the tool head plate I I9, and is further journaled at its lower end in a bracket 2 I4, likewise carried by the tool head plate II9. As will be seen from Fig. 25, the housing 2I0 is provided at its lower end with a shoulder 2I5 on which rest an enlarged collar 2I6 of the pin 209. A coil spring 2 I I surrounds the pin 209 and abuts with the collar 2 I 3 for maintaining the pin in its normal lower position. The normal position of the pin 209 is in line with the pin 208 and a valve actuating slide 2I8, the lower end 2I9 of which it engages during the'upward movement of the spindle carrier for thereby upwardly shifting the said slide 2 I8, as seen in Fig. 24.

The slide 2 I8 is adapted to slide against the face 220 of the head plate II9 of the tool head IOI. The slide 2I8 is retained in position by a flange 22I projecting from a bracket 222 secured to the head plate II9. This slide 2 I8 is provided intermediate its ends with rack teeth 223 meshing with a segmental gear 224, rotatably mounted on the bushing I46 carried by the tool head plate I I9.

' The segmental gear 224 has projecting rearwardly therefrom an arm 225 provided at its rear end with a circular head 225 contacting on opposite sides thereof with valve stems 221 and 228. The valve stems 227 and 228 are associated with valve mechanisms which operate pistons for shifting the main control valve member I28, and these valve members are respectively shown diagram: matically in Fig. 26 where they are respectively indicated in general by the reference characters 229 and 230.

This upward movement of the valve slide 2I8, through its rack teeth 223, oscillates the arm 225 for shifting the valve stem 228 of valve mechanism 239. The valve mechanism 239, as noted above, is shown diagrammatically in Fig. 26 and is shoWn structurally in Fig. 15. The valve stem 228 has connected therewith a valve member 23I having intermediate its ends a reduced portion or cannelure 232. Below the cannelure 232, the valve stem 23I is provided with a counterbore in which is disposed one end of a coil spring 233, which has its other end seated in the counterbore of a plug 234 in the end of the bore in thevalve block I35 which accommodates the valve 23I; The valve member 23I is provided with a flange 235 to engage a shoulder 230 to limit the movement thereof by the spring 233.

As shown in Fig. 26, the reduced portion or cannelure 232 normally connects ports 23? and 233, and when operated by the arm 225, connects the ports 233 and 239. The port 239 has connected therewith one end of a branch pressure pipe or conduit 240, while the port 231 has connected therewith one end of a pipe or conduit 24 I which terminate in the sump or tank III. The remaining port 238 has connected therewith one end of a pipe or conduit 242,.terminating at its other end in a cylinder 243. While the connection between the ports of the valve mechanism 230 is illustrated, in Fig. 26, as pipes or conduits, they are in fact merely cross-drilled ports in the valve block I35.

The cylinder 243 is in effect a cylindrical bore in valve block I35, which has disposed therein a piston 244, engaging the undersurface of the valve shifter arm I47. The operation of the piston 244 shifts the main control valve 523 to its extreme left hand position, thereby connecting the pressure in the pipe or conduit H4 with the top of the cylinder I99 for actuating the piston 99 therein downwardly at a rapid rate. The fluid ahead of the piston 56 is forced through the pipe or conduit I39, to the main control valve I28, where it is connected with the pipes or conduits I40 and MI and the sump or tank III, thereby rapidly advancing'the tool to the work.

From the foregoing, it will now be noted that the dog 29?, through its pin 208 and the inter mediate pin 209, reverse the movement of the tool carrier. It should be noted at this time that this reversal took place at a point short of the initial position of the tool carrier, and from which initial position the carrier was actuated by the manual operation of the iover IOI, all as will be later made clear.

The rapid advance of the tool carrier continues downwardly until the rapid traverse cumulative dog I54 through its nose i555 engages the flipper dog Ifii and shifts the main control valve I28 to the slow feed position, whereupon, the tool carrier advances at a slow rate, as above described. This slow movement of the tool carrier continues until the torque control mechanism again. withdraws the tool or until a.

definite amount of tooling or drilling has taken place, for example-one inch or more. In order to-reverse the tool carrier and withdraw the drill from the work after a pre-determined amount of drilling has-taken place, the following mechanism is employed.

. Mounted on the dog rod or bar I53, as seen in Figs. 10,22 and 24, is a slow feed dog 245 having projecting from oneside thereof an arm 246 into which is threaded a dog screw 241 having a nose 248. The dog screw 24'! islocked into adjusted position by lock nut 249. The adjustment of the dog screw 241, and the distance between the end of its nose 248 and the end of cam nose I55 of the cumulative rapid traverse dog 156, "determines the amount of drilling or the amount of slow teed movement imparted to the. tool carrier before reversal thereof. This feed dog 245 is loosely mounted on the dog rod I53 andis connectedthereto by means of a pall 250 disposed ins. .slot 251 formed in the dog 245 and pivotly connected by means of pivot 252. The upper end of the pall 250 :has projecting therefrom .a pin '253 to which is connected one end of a spring 25.4 which has its other end connected with a second pin 255 projecting. from the :dog 245, see Eig.:2l. 'This spring maintains the pointed nose 256 of the pall 250 inengagement withratchet teeth25! formed on the inner face of the dog rod I53. From the foregoing, it willbe seen that even though the feed do 245 is loosely or slidably mounted on the dog rod I53, it is positively and mechanically connected therewith. The feeddog 245 is maintained indefinite spaced relationwi-th the cumulative rapid traverse dog by means of a spring 258 disposed around the dog. rod I53and abutting at opposite endswith said :dogs. In order to maintain said dogs in spacedrelationwith one another, use is made .ofta tie rod-or bolt 259 which. has its l'owerend threaded into the rapid. traverse dog and its upper-end. passing through a plane perforation in the said feed dog with ahead at the upper end of the tie rod .prbolt 259 engaging the upper surface of feed dog 245.

When the tool carrier reaches the end of the {JIB'edQliGlIIlihBd amount .of drilling the nose 21-18 of the :dogscrew 24.! engages the upper end 250 of, yalveactuating, slide, 218 and causes adow-n- Fw'ardshifting thereof. :This downward movement of the ,valve slide. 2!.8 through. its rack teeth .2 23 rotates the segmental gear 224 to cause an upward oscillation of its arm 225 which through the enlarged ballend thereof. iactuates the valve stem 22'! of valve mechanism 229.

. The valve mechanism, 229 is illustrated structurallyin Figs. 15 and 17 and comprises a valve member ,25I integral with the valve stem..22| which has a reduced .portionor cannelure .2 52 intermediate the ends thereof. The. valve memberg2fil is mounted in a .bore in. the valve block ;I.-I8,,which is provided with 'threeports 263,254 and 265. The valve member 2'6I is adapted, when inthe position shown, to connect the ports .264 and255, and when in its second positioii to cutiofi the port 265 and connect the ports264 and :263. The valve is shifted to the position shown bymeans of a spring 266 disposed in a counterbore in the upper endof the valve member-, having its other end seated in a counterbore in a plug 251 secured in the upper end of the valveiocre. It should be noted atthis time that the'plu'g 251 is of aslightly greater diameter than the-valve member 25 I thereby providing a; shoulder 268 Y against. which an --en1argedcollar portionof the valve member 26! engages .to limit the movement of the valve member by the spring 256; Asseen in Fig. 26, the port 253 has connected therewith oneend of a branch pressure pipe or conduit-259 which extends from the main pressure pipeconduitl I4, while .the.port 265 has connected therewith one end of a .drain .pipe .or conduit 270, which terminates at the sumpor tank III. The remaining port 254 is illustrated in Fig.26 as a pipe or conduit 2 and terminates iria cylinder 272. This cylinder is illustrated in Fig. 15 as a bore. in which ismounted a piston 23.3 which has its lower end in contact with the upper surface of valve shifting arm I4'I.

'From the foregoing it will nowbe seen that engagement of the dog :screw .241 withthe slide 2L8 causes same to actuate the arm v225 and shift valve 26I, thereby connecting pressure in the pressure line H4 through thepipe or conduit 259 and cannelure or reduced portion 262 with the pipeor conduit 2' and cylinder 21.2, for actuating the valve arm 14'! for shifting the main control valve member I28 to its-extreme righthand position, as seen in Fig. 26. The shifting of the valve member I28 to its right hand position connects the pressure in the pipe or..conduit IE4 with the pipe .or conduit I39, thereby elevating the piston .99, and parts connected therewith, .at. a rapid rate. The fluid ahead. of the piston 99 is exhausted by way of the, pipe .or conduit 38, main control valve I28 and pipe or conduit I to the sump ,or tank III.

It should be here noted that during the slow or feed movement of the tool carrier the feeddog 255 was actuated toward the cumulative rapid traverse stop dog E55 and that the. frictional connection of the cumulative rapid traverse stop dog i565 causes the feed dog to move upwardly with the carrier and that the saidcumulative rapid traverse. stop dog is therefore now positioned on the dog rod orbar I53 at a point where the previous slow movement or drilling of the work stopped.

During this upward movement of the carrier, whether caused by the torque control mechanism or by thefeed dog, a cam. plate 274, carried by the .tool head and having a earn 215 thereon, engages .2. lug or knob 216 on the feed dog latch or pawl .2 for actuating same about its pivotal mounting 2.52 for disengaging its nose 256 from the rack teeth, 251. Upon the disconnection of thefeed d0g245 from the dog bar I53, thespring 258, compressed during the previous slow feed movement of the carrier, expands for separating the cumulative rapid traverse stop and feed dogs an amount determined by the connecting pin or bolt 259and again positions the feed dog to permit its subsequent operation. It will be appreciated, of course, that this feed dog may not have operated to reverse the carrier, which may have been accomplished by the torque controlling mechanism, but, nevertheless, the feed dog was actuated toward the cumulative stop dog whose movement was arrested by engaging the top face or surface 211 of the bracket 2I4 immediately after the operation of the flipper I6 I.

After each rapid retraction of the tool carrier, whether caused by the torque control orslow feed dog, the rapid downward movement of the car rier, and parts carried thereby, continues until the cumulative stop'dog, through its cam I55 again shifts the flipper I64 for slowing down the movement of the carrier to a feeding rate. The feed then continues until the drilling distance, as established by the spacing of the feed dog nose 248 from the cumulative stop dog nose I55, has taken place, or until the torque on the drill reaches the point for substantially slowing down the rotation of the tool or drill spindle, so that its microswitch contacts 11, and I89 closes, whereupon the carrier is reversed to retract the tool from the work and effect a clearing of the chips from the hole being bored and a drenching of the tool or drill with coolant.

This cycle of operation is repeated continuously until the hole is completely bored through, whereupon the parts are returned to their initial position and the movement of the tool carrier stopped.

The mechanism for returning the carrier to its initial position, and stopping the mechanism, comprises a cam dog 218, see Fig. 1, which has a cam face 219 and is adjustably positioned in the T-slot I50 in the carrier. This dog 218 is adjusted to the point where it comes into operation after the work has been completely bored, and is adapted to engage the end 280, see Fig. 23, of a short rack 28I mounted for transverse movement in the bracket 2I4. The rack 28I has its teeth 282 meshed with a pinion 283, keyed or otherwise secured to the rod 2 I2, which, as noted above, carries at its lower end the arm 2I I. This rod H2, in addition, has secured thereto a resetting member 284, see Figs. and 21, having a lug 285 adapted to overlie a lug 286 projecting from the side of the cumulative rapid traverse stop dog I56.

When the tool or drill of the carrier has completely bored the hole being drilled, the cam dog 218 shifts the rack 281 outwardly, as seen in Fig. 23, or to the right, as seen in Fig. 1, thereby oscillating the rod 2I2. This oscillation of the rod 2I2 carried with it the arm 2I I and removes the intermediate pin 209, carried by its outer end, from the path of movement or" the dog pin 208, so that the upward movement of the cam slide 2I8 cannot be effected. This then permits the carrier to travel beyond the point where it is normally reversed by the dog 281. In order to stop the carrier at its upper limit of movement, it has projecting from it, see Fig. 24, a pin 281, which engages the projecting end 288 of an arm 289 keyed or otherwise secured to the inner end of the flipper dog stud or shaft I52, as seen in Fig. 20. This stud or flipper dog shaft I62 is connected, through the seat and lug I63 and I64, with the lever I54, and therefore the valve member I28, for shifting the valve to its stop or neutral position. In order to initiate further operation of the machine, it is necessary to shift the valve to position by the lever I44.

The oscillation of the rod 2I2, as above described, also shifts the resetting member 284 to the position to cause the projection 235 to overlie the cumulative stop dog lug 286 and thereby hold the said dog relative to the dog bar I53 during this final upward movement of the carrier, and thereby positioning the cumulative rapid traverse stop dog to its initial position for a subsequent operation of the machine. The repositioning of the cumulative rapid traverse stop dog through its connecting pin or bolt 259, correspondingly positions the feed dog 246 on the dog bar. The operation of the handle or lever I, for starting up the machine, effects the oscillation of the rod 2I2, so as to free the cumulative stop dog from its resetting member 284, as well as to position the pin 259, for subsequently reversing the direction of movement of the tool carrier. This resetting of the parts takes place through a cam 16 290, on the lever I44, which engages the end 291 of the rack 28I for shifting it in a direction reverse to that in which it was shifted by the cam dog 218.

In order to hold the rod 2I2 in either of its two operative positions, it has keyed or otherwise secured to it, at a point below the bracket 2I4, a detent plate 292, provided in its one end with a pair of notches 293 and 284, which co-operate with a spring pressed detent 295. The detent member 295 is disposed in an enlarged bored portion 296 of the bracket 2M which contains a spring 291 abutting on its inner end with the detent 295, and on its outer end with a plug 298.

From the foregoing, it will now be appreciated that there has been provided a deep hole or step drilling machine, in which the tool is actuated through repeated cycles of a rapid movement toward the work, a slow movement through a portion of the work, and a rapid movement from the work. The control of this cycle is dependent largely on the torque on the drill or tool during its operation, which control may be supplemented by means for periodically clearing the hole of chips to insure accuracy in drilling, and ultimate safety of the drill. It will be appreciated that the idle time of machines as heretofore known and used has been greatly reduced, while the mechanism is held to ultimate simplicity when considering the necessarily involved circuit.

What is claimed is:

1. In a drilling machine of the class described a spindle drive comprising a prime mover, a spindle, a driving sleeve splined to said spindle, means supporting said driving sleeve for rotation, a pulley freely rotatable on said sleeve, a power transmission member between the prime mover and sleeve pulley, and a yieldable coupling between the pulley and the sleeve for permitting continued pulley rotation While spindle rotation is retarded by torque thereon and automatically re-establishing spindle and pulley unitary rotation upon removal of torque on the spindle, including a plurality of driving dogs upstanding from said pulley, a rockable driven dog and cam member carried by the spindle driving sleeve in driving engagement with each of said pulley driving dogs, and a spring tension device for holding the said driven dog and cam members against rocking and in operative positions during normal torque on the spindle driving sleeve.

2. In a drilling machine of the class described a spindle drive comprising a prime mover, a spindle, a driving sleeve splined to said spindle, means supporting said driving sleeve for rotation, a pul ley freely rotatable on said sleeve, a power transmission member between the prime mover and sleeve pulley, a yieldable coupling between the pulley and the sleeve for permitting continued pulley rotation while spindle rotation is retarded by torque thereon and automatically re-establishing spindle and pulley unitary rotation upon removal of torque on the spindle, including a plurality of driving dogs upstanding from said pulley, a rockable driven dog and cam member carried by the spindle driving sleeve in driving engagement with each of said pulley driving dogs, and a spring tension device for holding the said driven dog and cam members against rocking and in operative positions during normal torque on thespindle driving sleeve, a movable spindle carrier rotatably supporting the spindle for movement relative to the driving sleeve toward and from work, means moving said spindle carrier, and means operable upon rocking of said rockable dog and cam members operating the spindle carrier moving-means to-retract the spindle and tool from the work.

3. m a drilling machine of the "class described aspindle "drive comprising aprime mover, aspindle, a drivingsleevesplinedto said spindle, means supportingsaid'driving sleeve for rotation, a pulleyfreely rotatable on said sleevega power transmission member between the prime mover and sleeve pulley, a 'yieldablecoupling between the pulley and "the sleeve for permitting continued pulley rotation while spindle rotation is retarded by torquethereon and automaticallyre-establishi-ng spindle and pulley unitary rotation upon removal-of torque on the spindle, including a pluralityof driving dogs upstanding from saidpulley, a rockable driven dog and cam member carried by "the Spindle driving sleeve in driving engagement with each o'f'said' pulley driving dogs, and a spring tension device for holding "said driven dog and cam members against rocking and in operative positions-during normal torque on the spindle "driving sleeve, a movable spindle carrier rotatably supporting the spindle for movement relative to the driving sleeve toward and from work, means moving said spindle carrier, electromagnetic means for operating the last mentioned means-and a controlswitch'operable by and upon the rocking of the dog and cam members for energizing the electromagnetic means and cause a retraction of the tool carrier from the work.

4. In -'a drillingmachine of the clas described a 'spindle'drive comprising "a prime mover, a spindle, 'a-drivingsleeve splined to-said spindle, means for supporting said driving sleeve for" rotation, a pulley freely rotatable on said sleeve, a power transmission member between the prime "mover and sleeve pulley, a-yieldable driveconnection between the pulley and the sleeve for permitting rocking movement except under overload torque continued "pulley 'rotationwhile spindle rotation is retarded by torque'there'on and automatically re-establishing spindle and pulley unitary rotation upon removal "of torque on the spindle; including driving dogs or 'abutments upstanding from said pulley, cooperating driven "dogs carried by the spindle driving sleeve, said driven dogs being movable "mounted whereby they may be-displaced upon increase in torque on the spindle driv'ingsleevea spring operable for holding said driven dogs in operative ,positions during normal torque on the spindle driving sleeve, means for establishing :said l-normal tor que, lazspindle carrier for mounting the spindle for movement relative'to the driving sleeve towardand fromwork, means for actuating said spindle carrier, electromagnetic means-operable by said displaced driven dogsupon displacement thereof "fOr operatingthe tool spindle carrier actuating means to retract the spindle :andtool from the work, and means operable by the .carrier after the electromagnetic means has been deenerg'ized for actuating the tool carrier toward the work.

5. In a drilling machine of the class described a spindle, a sleeve splined to said spindle, means supporting said sleeve for rotation, a pulley freely rotatable on the sleeve, a prime mover, power transmission means between the prime mover and pulley, a plurality of driving dogs projecting from said pulley, a plurality of rockable dog and cam members for and having a shoulder in abutment with each pulley driving dog, a radial pin for each dog and cam member projecting from said sleeve on which said dog and cam members are rockably mounted, and a sprin tensioning device for holding said dog and cam members against on the spindle.

v 6*.- In a drilling machine of the class described a spindle, a sleeve splined to said spindle, means supporting said sleeve for rotation, a pulley freely rotatable on the-sleeve, a prime moven'power transmission means between the primemover-and pulley, a plurality of driving dogs projecting from said'pulley, a plurality of rockable dog and cam members "for and having a shoulder in abutment with each pulley driving dog, a radial pin :for each dog and cam' member projecting fromsaid sleeve on which said dog and cam members are rockably mounted, and a spring tensio-ning device for holding said dog and cam members against rocking movement except under overload torque on thespindle,-and said'dog and cammembers each including -a cam "face on which the spring-tensioning device operates.

"l. Ina-drilling machine of-th'e class describedn spindle, a sleeve splined to said spindle, means supporting said sleeve for rotation, a pulley freely' rotatable on the sleeve, "a'prim'e mover, power transmission means between the prime mover and pulley, a plurality of driving dogs projecting from said pulley, a plurality of rockable dog and cam members for and having a shoulder in abutment with each 'pulley driving dog, a radial pin for each dog "and cam member :projecting from said sleeve on which said dog and cam members :are rockably mounted, and a spring tensioning 'device for holding said dogand cam members against rocking movement exceptunder overloadtorque on the spindle, said dog and cam-members each includin a cam face on which the spring tensioning device operates, "a movable-spindle carrier rotatably suppporting the-spindle for movementrielative to the sleeve-toward and-Hom work, means formoving-sa'id'spindle carrier, "andmeans operable upon rocking of said rockable "dog and cam members for operating the spindle carrier moving means'to retract -the spindle carrier and spindle'fromthe'work.

8. In a drilling-machine of the class described a spindle, a sleeve splined to said spindle, means supporting said'sleeve f or rotation, a pulley freely rotatable on the sleeve, a prime mover, power transmission means "between'the prime vmover and "pulley, "a plurality of driving 'dogs 'proj ecting from said pulleyfaplurality 'of rockable dog "and faces ofthe dog :and {cam members, a spring holding said plate in contact with said rockable dog and cam members faces displaceable upon rocking of said do and cam members, a movable spindle carrier rotatably supporting the spindle for movement relative to the sleeve toward and from work, said spindle carrier having a definite stroke length, means including control means moving said spindle carrier, electromagnetic means effecting the operation of the control means, and a switch operable by the spring tensioning device plate upon displacement thereof for energizing the electromagnetic means.

9. In a drilling machine of the class described a spindle, a sleeve splined to said spindle, means supporting said sleeve for rotation, a pulley freely rotatable on the sleeve, a prime mover, power transmission means between the prime mover and pulley, a plurality of driving dogs projecting from said pulley, a plurality of rockable dog and cam members for and having a shoulder in abutment with each pulley driving dog, a radial pin for each dog and cam member projecting from said sleeve on which said dog and cam members are rockably mounted, and a spring tensioning device for holding said dog and cam members against rocking movement except under overload torque on the spindle, said spring tensioning device including a plate in contact with the cam faces of the dog and cam members, a spring holding said plate in contact with said rockable dog and cam members faces displaceable upon rocking of said dog and cam members, a movable spindle carrier rotatably supporting the spindle for movement relative to the sleeve toward and from work, said spindle carrier having a definite stroke length, means including control means moving said spindle carrier, electromagnetic means effecting the operation of the control means, a switch operable by the spring tensioning device plate upon displacement thereof for energizing the electromagnetic means, and additional dog means on the tool carrier actuating the control member to a position to cause the spindle carrier moving means to retract the spindle carrier from the work.

10. In a drilling machine of the class described a spindle, a sleeve splined to said spindle, means supporting said sleeve for rotation, a pulley freely rotatable on the sleeve, a prime mover, power transmission means between the prime mover and pulley, a plurality of driving dogs projecting from said pulley, a plurality of rockable dog and cam members for and having a shoulder in abutment with each pulley driving dog, a radial pin for each dog and cam member projecting from said sleeve on which said dog and cam members are rockably mounted, and a spring tensioning device for holding said dog and cam members against rocking movement except under overload torque on the spindle, said spring tensioning device including a plate in contact with the cam faces of the dog and cam members, a spring holding said plate in contact with said rockable dog and cam members faces displaceable upon rocking of said dog and cam members, a movable spindle carrier rotatably supporting the spindle for movement relative to the sleeve to- Ward and from work, said spindle carrier having a definite stroke length, means including control means moving said spindle carrier, electromagnetic means eilecting the operation of the control means, a switch operable by the spring tensioning device plate upon displacement thereof for energizing the electromagnetic means, additional dog means on the tool carrier actuating the control member to a position to cause the spindle carrier moving means to retract the spindle carrier from the work, and means operable by the spindle carrier at the end of its stroke actuating the control member to a position to cause the spindle carrier moving means to retract the spindle carrier from the work.

11. In a drilling machine of the class described a spindle, a sleeve splined to said spindle, means supporting said sleeve for rotation, a pulley freely rotatable on the sleeve, a prime mover, power transmission means between the prime mover and pulley, a plurality of driving dogs projecting from said pulley, a plurality of rockable dog and cam members for and having a shoulder in abutment with each pulley driving dog, a radial pin for each dog and cam member projecting from said sleeve on which said dog and cam members are rockably mounted, and a spring tensioning device for holding said dog and cam members against rocking movement except under overload torque on the spindle, said spring tensioning device including a, plate in contact with the cam faces of the dog and cam members, a spring holding said plate in contact with said rockable dog and cam members faces displaceable upon rocking of said dog and cam members, a movable spindle carrier rotatably supporting the spindle for movement relative to the sleeve toward and from work, said spindle carrier having a definite stroke length, means including con-v trol means moving said spindle carrier, electromagnetic means effecting the operation of the control means, a switch operable by the spring tensioning device plate upon displacement thereof for energizing the electromagnetic means, additional dog means on the tool carrier actuating the control member to a position to cause the spindle carrier moving means to retract the spindle carrier from the work, means operable by the spindle carrier at the end of its stroke actuating the control member to a position to cause the spindle carrier moving means to retract the spindle carrier from the work, and additional means operable by the spindle carrier at the beginning of its stroke actuating the control means for stopping the spindle carrier moving means. I

EDWARD J BUSEMEYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 447,413 Perry Mar. 3, 1891 1,229,570 Backscheider June 12, 1917 1,883,164 Vassakos Oct. 18, 1932 2,260,327 McKee Oct. 28, 1941 2,418,220 Churchill Apr. 1, 1947 

